Fuel cell systems generate electrical power from an electrochemical reaction between a fuel and an oxidant. Many fuel cell systems use a gaseous fuel such as molecular hydrogen, and a gaseous oxidant such as molecular oxygen. Air is commonly used as the source of oxygen. The reaction between hydrogen and oxygen generates water which is exhausted in the waste gases of the fuel cell.
Many fuel cells, and especially fuel cells for automotive propulsion, are based on proton exchange membrane (PEM) technology. These fuel cells contain PEM membranes that operate in the range of about 50-120° C., and which must be kept moist for optimal performance and durability of the fuel cell.
Where air is used as the gaseous oxidant, it is brought up to the fuel cell's operating pressure by an air compressor before it is fed to the cathode of the fuel cell. However, during compression, the air can be heated to a temperature of about 200° C. or higher, which is considerably higher than the operating temperature of the fuel cell. Therefore, the pressurized charge air must be cooled to the desired temperature by a charge air cooler before it reaches the fuel cell stack.
A humidifying device may be located in-line between the air compressor and the fuel cell stack in order to increase the moisture content of the charge air to a sufficient level to prevent dehydration of the fuel cell's membranes. It is known to humidify the charge air by transfer of water vapour from the waste gases of the fuel cell, for example as disclosed in published patent application no. US 2012/0181712 A1 by Vanderwees et al. (referred to herein as Vanderwees '712), or WO 2013/092630 A1 by Stroebel et al., both of which are incorporated herein by reference in their entireties. Where the humidifying device is a membrane humidifier as disclosed by Vanderwees et al., it will have an operating temperature significantly lower than the temperature of the pressurized charge air. Therefore, it is also desirable to cool the charge air before it reaches the humidifying device.
It is apparent from the preceding discussion that numerous components are required for processing feed gas streams and exhaust gas streams in a fuel cell system. In vehicular systems in particular, these components must all fit within a finite space. Therefore, in order to save space, reduce cost, and simplify the complex nature of these systems, there is a need to provide integrated gas management devices which reduce the number of components and provide more direct connections between the components. It is nevertheless required that these systems are tightly sealed in their entirety.